From Event: SPIE Organic Photonics + Electronics, 2015
Cholesteric liquid crystals with helicoidal molecular architecture are known for their ability to selectively reflect light with the wavelength that is determined by the periodicity of molecular orientations. Resulting interference colors are highly saturated, they add like colored lights and produce a color gamut greater than that obtained with inks, dyes, and pigments. The periodicity of the helical structure and thus the wavelength of the reflected light can be controlled by chemical composition and sometimes by temperature, but tuning with the electric field has been so far elusive. Here we demonstrate that by using a cholesteric with oblique helicoidal (heliconical) structure, as opposed to the classic “right-angle” helicoid, one can vary the wavelength of selectively reflected light in a broad spectral range, by simply adjusting the electric field applied parallel to the helicoidal axis. The effect can enable many applications that require dynamically controlled transmission and reflection of light, from energy-saving smart windows to tunable organic lasers, and transparent “see-through” displays. Since the material is non-absorbing and transparent everywhere except the electrically preselected reflection band, the effect can be used in creating multilayered structures with a dynamic additive mixture of colors.
Oleg D. Lavrentovich, Jie Xiang, Sergij V. Shiyanovskii, and Quan Li, "Electrically tunable selective reflection of light by heliconical cholesteric structures (Presentation Recording)," Proc. SPIE 9565, Liquid Crystals XIX, 95650F (Presented at SPIE Organic Photonics + Electronics: August 09, 2015; Published: 5 October 2015); https://doi.org/10.1117/12.2185601.4519371773001.
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